1. Field of the Invention
The present invention relates generally to the manufacture of a surface-type fastener having a number of interlocking elements such as loops or hooks projecting from one surface of a woven foundation fabric. More particularly, it relates to a mandrel for use with a loom for the formation of the loops in synchronism with the weaving of the foundation fabric on the loom.
2. Prior Art
U.S. Pat. No. 3,009,235, issued Nov. 21, 1961 discloses, as reillustrated here in FIGS. 6 and 7, a mandrel A used for the formation of loops B on a woven fabric C. The disclosed mandrel includes a loop-forming portion D of reduced section on which the loops B are formed, and a loop-setting portion E of larger section adapted to tension the loop B after their formation for insuring the formation of a firm fabric with the upstanding loops positioned in a uniform manner.
Since the loop-forming portion D of the disclosed mandrel A has a uniform height throughout the length threof, it is not possible to rectify or correct the deviation of a loop-forming warp thread F from its desired course which would occur when the warp thread F is looped successively around the loop-forming portion D due to, for example, the flexibility of or the initial twisting of the warp thread F. Consequently, successive loops B are formed at different positions on the loop-forming portion D and hence they are subjected to random tensioning forces when advanced to the loop-setting portion F. The final loops B set on the loop-setting portion E have different shapes and configurations and are positioned in a non-uniform manner. Due to the above-mentioned deviation, the loop-forming warp thread F is likely to interfere with a foundation weft thread G prior to the latter is interlaced with a series of foundation warp threads H (two being shown) and with the warp thread F. This interference result in a weaving failure and non-uniform loop formation.
A further disadvantage associated with the mandrel A is in that since the loop-setting portion E has a uniform height, the loops B, as they are advanced along such portion E, are subjected to undue frictional forces which would cause deformation or twisting of the loops B.